The present invention and its underlying problems are described hereinafter with regard to a device under test (DUT) which is designed as a base station, however, without limiting the invention to it.
In radio communications, a base station (or base radio station) is a wireless communications station installed at a fixed location and used to communicate as part of a wireless telephone system, such as a cellular CDMA or as a cell of a GSM, UMTS, LTE or 5G network. A wireless base station is configured to communicate with a mobile device, such as a mobile phone, smart phone, tablet, router, etc. For example, in a wireless telephone system, the signals from one or more mobile devices in an area are received preferably at a nearby base station, which then is able to connect the call to a land-line network or directly to another nearby mobile device.
A base station of a wireless communications system needs to be tested prior to their use. In particular, in the very last step of a production line, it is essential to test if mounting the antenna on a base station adversely affects the performance of this base station. In the state of the art, test systems are known which are used for testing a device under test, for instance a 4G or 5G communication device. The test system usually comprises an anechoic test chamber and an antenna arrangement which is arranged inside the test chamber. Such a test system is described, for example, in EP 3 312 619 A1.
While testing small portable mobile devices is comparatively manageable, testing a base station and its antenna arrays requires much more effort simply because of their overall size. In particular, a test chamber must be provided here, which is dimensioned to accommodate a base station. The so-called OTA (over the air) testing of the antenna elements of the base station plays a special role here. In addition, base stations are high-power devices which, especially due to their high transmission power, during testing produce a considerable amount of heat which may influence the test results negatively. Therefore, known test systems use correspondingly large test chambers, which, however, are not suitable for testing a base station in production lines and which are also cost-intensive. Smaller sized test chambers can be equipped with an appropriate cooling equipment to largely reduce the effects caused by heat generation. However, the cooling is quite complex and therefore cost-intensive.
This is a situation that needs to be improved.